Brittenburg

The site was about a kilometre west of the European Space Research and Technology Centre, now offshore in the North Sea).

[2] All that remains is a small set of finds, collected in the sixteenth and seventeenth centuries, and a famous map by Ortelius.

Along the northern route, the following towns can be seen: Pretorium Agrippine (Valkenburg (South Holland)), Matilone (Leiden), Albaniana (Alphen aan den Rijn), Nigropullo (Zwammerdam), and Lauri (Woerden).

[3] The first mention of the Brittenburg in a Dutch text is in a poem of Willem van Hildegaersberch in 1401, who called it Borch te Bretten.

The oldest picture of the Brittenburg is a woodcut (identified by Leiden professor Jan Hendrik Holwerda, curator of the Rijksmuseum van Oudheden) by Abraham Ortelius in 1562 for Lodovico Guicciardini's first edition of The Low Countreys, printed in 1589 by Christophe Plantin in Antwerp.

It concerns a land surveyor's draft (trigonometry), in which the distance from the ruins (by that time in the North Sea and only visible at low tide) westward to the church of Katwijk is mentioned, namely 1,200 'schreden' (= 1,080 meters).

The name is doubly unfortunately chosen, as those same scholars also assumed that Leiden was located within the old Batavia (region), which was in fact much further east, near Germany.

Furthermore, it is possible that Suetonius was purposely manipulating the facts to make Caligula seem worse by playing off the word musculus's double meaning as both "seashell" and "mantlet," a type of military shield.

[6] Considered to be part of Lugdunum, the Roman army supply base Praetorium Agrippinae, modern Valkenburg, is said to have been founded by Caligula.